This invention relates to the production of thixotropic silicates from natural silicates and, in the process, produces a stable organic compound-thixotropic silicate emulsion. The stable organic compound-silicate emulsions are produced by mixing and reacting a finely-powdered, natural silicate and a salt-forming compound, containing water in a liquid organic compound.
It is well known in the arts that a water-soluble alkali metal silicate may be reacted with an acid compound to produce a precipitated silica that, when dried, has thixotropic properties and will function as a thickening agent. The soluble alkali metal silicates are considerably more expensive than powdered natural silicates. When natural silicates are reacted with a salt-forming compound in an aqueous solution, the dried silicate has poor thixotropic properties. I have discovered that when the powdered natural silicates are reacted with a salt-forming compound containing water, in a liquid organic compound, it becomes a very good thixotropic agent. The thixotropic silicates are inexpensive and they also contain active oxide, hydroxyl and silicic acid radicals which can be reacted with organic compounds, silicon halide compounds and other inorganic compounds. An excess amount of the thixotropic silicate may be used as an inexpensive filler. When the powdered natural silicates are reacted with a salt-forming compound containing water without being in an organic liquid, the free hydroxyl and acid radicals react with each other to form clumps of natural silicates and require re-grinding to a fine powder. Most of the thickening properties are lost with the loss of the free oxide, hydroxyl and acid radicals.
The liquid organic compound may function only as a liquid medium for the reaction to take place in. After the reaction is completed, the liquid organic compound may be filtered off; then the remaining liquid may be evaporated off, thereby producing the thixotropic natural silicate with free oxide, hydroxyl and silicic acid radicals which, when added to liquid organic resins, e.g., polyols, polyesters, epoxy, phenoplast, aminoplasts, vinyl resins and paints, acts as a thickening agent, forming stable emulsions and stable sag-resistance emulsions.
Thixotropic natural silicates are produced by mixing and reacting the following components in an organic liquid:
A. finely-powdered natural silicate; PA1 B. salt-forming compound; PA1 C. water. PA1 (a) 1 to 50 parts by weight of natural silicate; PA1 (b) 25 parts by weight of liquid organic compound; PA1 (c) 0.1 to 10 parts by weight of a salt-forming compound; PA1 (d) 0.1 to 10 parts by weight of water; PA1 (e) up to 10% by weight of an emulsifier; PA1 (f) up to 10% by weight of a foam stabilizer; PA1 (g) up to 50% by weight of a blowing agent; PA1 (h) up to 10% by weight of an initiator.
The process of this invention also produces a stable organicsilicate emulsion.
Any suitable liquid organic compound may be used in this invention. Suitable liquid organic compounds include aliphatic, cycloaliphatic, aromatic, heterocyclic and mixtures thereof. Any liquid organic compound which will react with the salt-forming compound before the salt-forming compound can react with the natural silicates are not suitable, e.g., many amine compounds. The organic compound may be both the liquid organic compound and the salt-forming compound, e.g., acetic acid, propanoic acid, chloroacetic acid, etc. The liquid organic compounds may be saturated or unsaturated and may be substituted, e.g., with halogen, nitro radical, sulfates, etc.